Over 15 million diesel-powered trucks and other diesel powered vehicles provide long-haul transport of goods throughout the United States. A common practice among truckers is to leave the large diesel engines that power these trucks running (i.e., idling) during overnight stops. This practice occurs for a number of reasons, such as (1) to keep the cab and the sleeper compartment warm or cool; (2) to keep the diesel fuel warm during the winter months; (3) to keep the engine warm to avoid cold starting problems; (4) to mask other noises; (5) to enable use of various electrical devices in the truck cab, etc. However, because these large engines burn significant amounts of diesel fuel and/or gasoline fuel to power their engines, an excess amount of fuel far greater than the amount needed is wasted to provide power for these benefits to the drivers. This fuel consumption needlessly consumes a non-renewable energy resource, burdens the costs of shipping goods with unnecessary expense, and increases maintenance costs due to the excess wear that results from running the engines for uses other than pulling a loaded trailer. Furthermore, idling results in significant amounts of pollution because the use of the fuel in the engines produces emissions, such as nitrogen oxides (“NOx”), which are harmful to the environment, and in increased health care costs to treat illnesses caused by the emissions from the engines.
In response to these negative concerns, federal, state, and local governments have made controlling motor vehicle emissions a major focus of environmental controls, and many have taken measures to control the pollution from motor vehicles. For example, in some jurisdictions, idling the engines of these transport vehicles for substantial periods of time violates various laws and regulations. Other jurisdictions have addressed this issue by providing economic incentives for achieving reductions in the emissions of pollutants. In such a plan, a central authority sets a limit or cap on the amount of a pollutant that can be emitted. Companies or other groups that emit the pollutant are given credits or allowances which represent the right to emit a specific amount of those pollutants. The total amount of credits cannot exceed the cap, limiting total emissions to that level. Companies that pollute beyond their allowances must buy credits from those who pollute less than their allowances. These transfers are referred to as trades. In effect, the buyer is being fined for polluting, while the seller is being rewarded for having reduced emissions.
A number of solutions to the idling problem have been developed and are currently in use. These conventional systems generally employ an auxiliary power unit (“APU”) that runs on diesel fuel and drives an electric alternator or generator to supply operating voltages for heating and cooling the cab and/or sleeper compartment (“cabin”) or recharging the truck battery. However, each of these conventional systems has one or more of the following disadvantages: (1) the engine of the APU is water cooled and must be tied into the radiator system of the truck or be provided with its own radiator, hoses, water pump, etc.; (2) the engine of the APU drives the alternator or generator via a belt drive, which is associated with reduced efficiency, reliability, and additional maintenance costs; (3) the APU mechanically drives the A/C compressor for an auxiliary cooling system located in the cabin of the truck; (4) the APU requires extensive integration into the truck fuel, cooling, exhaust and electrical systems, which increases the cost of installing and maintaining the APU and reduces the reliability of the combined systems; (5) the integration of the APU into the truck systems increases the mechanical complexity thereof resulting in reduced reliability; (6) the APU is unable to monitor the amount of emissions the vehicle produces; and (7) the APU itself tends to be heavier and less efficient than it could be using modern technology.
As an illustration, conventional auxiliary power units are typically liquid cooled and require a radiator, a water pump, hoses, thermostat, etc., along with the mechanical structure to support them. Conventional auxiliary power units also use some form of adapter that employs a belt, chain, clutch or gear set to couple the engine to the generator, which adds weight, mechanical complexity and additional maintenance requirements. The additional circuitry adds weight, complexity, maintenance requirements and cost, all without improving the conversion efficiency of the auxiliary power unit. Efficiency is reduced in any of these conventional auxiliary power units because the motive power supplied by the engine must be large enough to overcome the extra losses associated with the more complex conventional auxiliary power units.